The present invention concerns a multipolar magnetizing device for permanent magnets, which is used for the magnetization of highly coercive magnets, such as those made of Alnico, hard ferrite, or rare-earth-cobalt alloys.
Such magnets are known to be magnetized primarily with a high current pulse through a current conductor which is arranged opposite the surface of the magnet, the current conductor having the desired number of poles and the desired pole arrangement. Thus, it is possible to generate poles on the circumference of cylindrical permanent magnets or on flat surfaces, such as the end face of annular magnets.
Known magnetizing devices consist, for example, of a soft iron body with grooves which are arranged so as to have the desired pole pitch and into which high current capacity conductors are inserted. These conductors must be insulated adequately to prevent electrical conduction with the soft iron conductor, whereby a considerable portion of the available space in the grooves is occupied by the insulation. This is especially true in the case of narrow pole pitches. In addition, it is difficult to sufficiently secure the current conductors against strong mechanical forces, despite attempts such as pouring plastic into the grooves.
Furthermore, no provision is made in the prior art for aligning magnet bodies having a preferred direction of magnetization. Such bodies are created by initially magnetizing them, then completely demagnetizing them during further processing operations (for example, during sintering of a body formed of prepressed parts or grinding of the outside diameter of a cylindrical magnet body). Re-magnetization is less efficient if the magnet body is not properly aligned so as to be remagnetized according to its preferred direction of magnetization.